Good morning everyone! Enjoy the calm before the storm as we are expecting a major severe weather and tornado outbreak tomorrow from portions of the Ohio Valley all the way to the Gulf Coast.

Let’s take a look at the set-up and why a widespread severe weather outbreak is likely:

A strong low pressure system will develop over the Southern Plains and move into portions of Northern Illinois by late Friday Evening. A strong southerly flow will help advect very warm and moist air into the Ohio and Tennesssee Valleys ahead of the low pressure system.

As the low pressure strengthens, a strong jet stream will interact with the system and create what we call directional wind shear. This wind shear is what helps storms form, sustain themselves and eventually begin rotating. Here’s a look at the wind shear tomorrow evening. The red and purple values are VERY high.

A strong southerly flow will usher in very warm and moist air into the Ohio Valley. Temperatures will climb into the 60’s as far North as North Central Indiana and Ohio. Here’s a look at what one of our forecast models is showing temperature wise tomorrow evening at 8:00 PM.

Storms should begin to fire across portions of Illinois down into Eastern Missouri and Arkansas by the mid afternoon hours. These storms will quickly move into the Ohio and Tennessee Valleys and portions of Northern Mississippi and Northern Alabama. All of the ingredients are in place for a very violent day of severe weather with the potential for very strong and long lived tornadoes.

Here’s a look at what one of our forecast models is forecasting radar reflectivity for tomorrow afternoon:

The Storm Prediction Center has issued a rare Day 2 Moderate Risk from Indiana and Ohio down to portions of Northern Mississippi and Northern Alabama. Here is a look at the Storm Prediction Center’s Outlook for tomorrow:

The storm prediction center is forecasting a severe weather event in the moderate risk area with widespread damaging winds and potential for strong and violent tornadoes.

Here’s our outlook for tomorrow which is very similar. The areas we outline as numerous and outbreak likely should be prepared for a very rocky day of weather.

We encourage everyone to have their severe weather plans ready and to purchase a NOAA weather radio! Stay tuned to SWAT & IndianaWeatherOnline for the latest information.

An extremely powerful early Fall weather system is brewing and will begin developing as early as tomorrow. A strong low pressure system induced by a strong polar vortex will merge and morph with a disturbance coming out of the Gulf of Mexico. This disturbance moving North out of the Gulf of Mexico will bring an abundant amount of moisture with it. As the warm and moist tropical air moves North, the warm and moist air (latent heat release) will help strengthen the morphed weather system as it travels North along the Spine of the Appalachian Mountains.

The water vapor imagery essentially tells the story this evening. You can see the large area of disturbed weather across portions of the Gulf of Mexico. The second system that will be a factor in this eventual large and phased weather system is a developing weather system across portions of Colorado. The extremely dry air across portions of Arizona and New Mexico is associated with our third player in this developing storm system and that is a very strong jet stream.

Nearly all of our forecast guidance has locked on to a solution of a strong weather system developing and moving into portions of the Midwest and Eastern Ohio Valley.

As the weather system begins to develop along the East Coast on Tuesday, strong and severe storms will be possible across the Southeastern United States. Increasing shear and an extremely tropical and buoyant atmosphere will lead to the threat of tornadoes from Florida into Georgia and eventually South Carolina.

This strengthening weather system will bomb out across portions of the Eastern Ohio Valley, strengthening possibly to as low or near 980 mb. This type of track is rare, as most storms that develop in this manner have a coastal low that transfers off the Mid Atlantic coast and tracks up the Northeast coast verses strengthening over land.

The track of his system means that a very large area will be impacted with heavy rain occurring from Florida all the way up the Appalachians, through the Ohio Valley and into portions of the Interior Northeast.

As the system reaches it’s peak intensity over the Eastern Ohio Valley and Eastern Great Lake states Wednesday and Thursday, extremely strong winds are also possible. You can see the tight wind field noted by the extremely close isobars around the low pressure.

With extremely impressive height falls as the low pressure deepens, it is not out of the question that some light snow could fall across portions of Northern Illinois, Southern and Eastern Wisconsin, Northern and Northwestern Indiana and Western Michigan. Obviously with extremely warm ground temperatures and fairly warm lower and mid level temperatures, no accumulation would occur, but the fact that some wet snowflakes are possible is definitely impressive.

La Niña, which contributed to extreme weather around the globe during the first half of 2011, has re-emerged in the tropical Pacific Ocean and is forecast to gradually strengthen and continue into winter. Today, forecasters with NOAA’s Climate Prediction Center upgraded last month’s La Niña Watch to a La Niña Advisory.

NOAA will issue its official winter outlook in mid-October, but La Niña winters often see drier than normal conditions across the southern tier of the United States and wetter than normal conditions in the Pacific Northwest and Ohio Valley.

“This means drought is likely to continue in the drought-stricken states of Texas, Oklahoma and New Mexico,” said Mike Halpert, deputy director of the Climate Prediction Center. “La Niña also often brings colder winters to the Pacific Northwest and the northern Plains, and warmer temperatures to the southern states.”

Climate forecasts from NOAA’s National Weather Service give American communities advance notice of what to expect in the coming months so they can prepare for potential impacts. This service is helping the country to become a Weather Ready Nation at a time when extreme weather is on the rise.

Seasonal hurricane forecasters factored the potential return of La Niña into NOAA’s updated 2011 Atlantic hurricane season outlook, issued in August, which called for an active hurricane season. With the development of tropical storm Nate this week, the number of tropical cyclones entered the predicted range of 14-19 named storms.

The strong 2010-11 La Niña contributed to record winter snowfall, spring flooding and drought across the United States, as well as other extreme weather events throughout the world, such as heavy rain in Australia and an extremely dry equatorial eastern Africa.

La Niña is a naturally occurring climate phenomenon located over the tropical Pacific Ocean and results from interactions between the ocean surface and the atmosphere. During La Niña, cooler-than-average Pacific Ocean temperatures influence global weather patterns. La Niña typically occurs every three-to-five years, and back-to-back episodes occur about 50 percent of the time. Current conditions reflect a re-development of the June 2010-May 2011 La Niña episode.

NOAA’s National Weather Service is the primary source of weather data, forecasts and warnings for the United States and its territories. NOAA’s National Weather Service operates the most advanced weather and flood warning and forecast system in the world, helping to protect lives and property and enhance the national economy. Visit us online at weather.gov.

NOAA’s mission is to understand and predict changes in the Earth’s environment, from the depths of the ocean to the surface of the sun, and to conserve and manage our coastal and marine resources. Join us on Facebook , Twitter and our other social media channels.

The 2010-2011 winter was the coldest winter in over 30 years across much of the Northeastern United States. Temperatures during the 200-2011 were well below normal in places like New York, Chicago, Indianapolis, Minneapolis and even New Orleans! Snowfall records were shattered across much of the Midwest and Northeast. With the 2010-2011 winter being so extreme, what can we expect for this upcoming winter?

The Winter forecast is compiled based on several factors. Analogs, Oceanic Temperatures, Climatology and Pattern Recognition are just a few of the factors used when making seasonal forecasts. Analogs in meteorology compare the current weather pattern to previous winter patterns. Oceanic temperatures refer to El Niño and La Niña which both refer to the Sea Surface Temperatures in the Equatorial Pacific.

One of the main factors used in my long range and winter forecasts are the Sea Surface Temperatures in the Equatorial Pacific and whether our weather pattern is being influenced by La Niña (cooler water temperatures in the Equatorial Pacific) or an El Niño (warmer water temperatures in the Equatorial Pacific). The Sea Surface Temperatures in the Equatorial Pacific provide a regulating force for North American Weather, particularly temperatures and winter storm tracks.

La Niña cools the equatorial seas of the Pacific and the 2010-2011 La Niña was one of the strongest on record. Less warm air rises during La Niña conditions with a cooling influence on the atmosphere that has significant implications on global climate and global weather patterns.

The upcoming 2011-2012 winter will likely be influenced by a weak to moderate La Niña. Oceanic temperatures in the Equatorial Pacific are already cooling and long range indications show a weak to moderate La Niña developing as early as this Fall.

La Niña conditions will likely start off fairly weak and strengthen as we head towards the middle and end of the winter. It will likely take much of the winter before the United States begins feeling the full impacts of La Niña, making the forecast two months of the forecast (December and January) much more difficult.

December looks to start off dry with warmer than normal temperatures as the jet stream will be displaced to the North and West. The far Northwestern United States will see above normal precipitation will the rest of the nation will see relatively quiet weather through the middle of December. With the jet stream displaced to the North, temperatures should climb to above normal values across much of the Nation through the middle of December. By the middle of December, the ridge will begin to break down as a major trough ejects south. As the trough ejects south, significant cyclogenesis (storm development) should occur across the Southern Plains and then transverse across the Central and Midwestern United States. A temporary Greenland Block by the end of December will lead to increased storminess and below normal temperatures across much of the Central and Eastern United States.

As the La Nina continues to try to build and take hold on the global circulation patterns, January will likely become a transition month. The main story during the month of January will likely be the extreme cold as the Polar Vortex should be displaced significantly farther South than normal. This will lead to a major arctic outbreak across the Eastern two thirds of the United States.

A La Niña like pattern will ensue during February leading to near normal temperatures across most of the Central and Eastern United States. A storm track from the South Central Plains through the Tennessee Valley and into the Middle Atlantic/Northeast will cause increased storminess and potential overrunning situations during the month of February. This will create an increased chance of snow and ice across the Midwest, Ohio Valley, Great Lakes, Middle Atlantic and Northeast.

With the La Niña pattern developing in February and influencing the global weather and circulation patterns, I would not be surprised to see a colder and snowier pattern continue into March. The potential for overrunning situations will continue into March with a continuing threat of snow and ice across the Midwest, Ohio Valley, Great Lakes, Middle Atlantic and Northeast.

Here are my ideas for the entire Winter as to who picks up above normal snowfall & ice. Obviously this is just based off of my forecast storm tracks, areas that receive above normal precipitation and either near normal or below normal temperatures.

In the end, I think the potential for record breaking cold across must of the Midwest, Great Lakes, Ohio Valley and even portions of the Northeast will be the big story this winter. Temperatures across the Plains should stay near normal with above normal temperatures across the Southern Plains and Deep South.

Don’t forget, you can book your 2012 Storm Chase Tour with SWATTours.com!

The NWS has issued a Heat Advisory today and an Excessive Heat Watch on Wednesday for all of Indiana and Western Ohio. Heat Index readings are expected to climb above 100 degrees through the end of the week. Below is a graphic detailing forecast heat index values through the end of the week.

Don’t forget that you can book your 2012 storm chase tour with SWATTours.com!

URGENT - WEATHER MESSAGENATIONAL WEATHER SERVICE INDIANAPOLIS IN311 PM EDT MON JUL 18 2011
..OPPRESSIVE HEAT AND HUMIDITY EXPECTED THIS WEEK
.A LARGE AREA OF HIGH PRESSURE ALOFT WILL INTENSIFY OVER THE
MIDDLE OF THE NATION...AND DRIFT SLOWLY EASTWARD. THE ASSOCIATED
HEAT AND HUMIDITY WILL ALSO BUILD EASTWARD...AND WILL ENGULF MUCH
OF THE MIDWEST. CENTRAL INDIANA WILL CONTINUE TO FEEL THE HEAT
THROUGH TODAY...WITH VERY OPPRESSIVE HEAT AND HUMIDITY EXPECTED
FROM TUESDAY THROUGH SATURDAY.
INZ021-028>031-035>049-051>057-060>065-067>072-190315-
/O.NEW.KIND.HT.Y.0003.110719T1800Z-110720T0100Z//O.EXT.KIND.EH.A.0001.110720T0100Z-110722T1900Z/CARROLL-WARREN-TIPPECANOE-CLINTON-HOWARD-FOUNTAIN-MONTGOMERY-BOONE-TIPTON-HAMILTON-MADISON-DELAWARE-RANDOLPH-VERMILLION-PARKE-PUTNAM-HENDRICKS-MARION-HANCOCK-HENRY-VIGO-CLAY-OWEN-MORGAN-JOHNSON-SHELBY-RUSH-SULLIVAN-GREENE-MONROE-BROWN-BARTHOLOMEW-DECATUR-KNOX-DAVIESS-MARTIN-LAWRENCE-JACKSON-JENNINGS-INCLUDING THE CITIES OF...LAFAYETTE...FRANKFORT...KOKOMO...
CRAWFORDSVILLE...ANDERSON...MUNCIE...INDIANAPOLIS...TERRE HAUTE...
SHELBYVILLE...BLOOMINGTON...COLUMBUS...VINCENNES...BEDFORD...
SEYMOUR
311 PM EDT MON JUL 18 2011
..HEAT ADVISORY IN EFFECT FROM 2 PM TO 9 PM EDT TUESDAY
...EXCESSIVE HEAT WATCH NOW IN EFFECT FROM TUESDAY EVENING
THROUGH FRIDAY AFTERNOON...
THE NATIONAL WEATHER SERVICE IN INDIANAPOLIS HAS ISSUED A HEAT
ADVISORY...WHICH IS IN EFFECT FROM 2 PM TO 9 PM EDT TUESDAY. THE
EXCESSIVE HEAT WATCH IS NOW IN EFFECT FROM TUESDAY EVENING
THROUGH FRIDAY AFTERNOON.
* THE COMBINATION OF TEMPERATURES IN THE 90S...AND HIGH
HUMIDITY...WILL PRODUCE DANGEROUS HEAT INDEX VALUES OF AROUND
105 DEGREES ON TUESDAY AND THEN 105 TO 110 DEGREES FROM EARLY
AFTERNOON INTO EARLY EVENING EACH DAY DURING THE WATCH PERIOD.
* THE IMPACTS OF HEAT STRESS ARE CUMULATIVE...AND INCREASE EACH
DAY THE HEAT LASTS. ANYONE SPENDING SIGNIFICANT AMOUNTS OF
TIME OUTDOORS...OR INVOLVED IN STRENUOUS ACTIVITY...WILL BE
SUSCEPTIBLE TO SERIOUS AND POTENTIALLY LIFE THREATENING HEAT
ILLNESSES.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
AN EXCESSIVE HEAT WATCH MEANS THAT A PROLONGED PERIOD OF HOT
TEMPERATURES IS EXPECTED. THE COMBINATION OF HOT TEMPERATURES AND
HIGH HUMIDITY WILL COMBINE TO CREATE A DANGEROUS SITUATION IN
WHICH HEAT ILLNESSES ARE POSSIBLE. DRINK PLENTY OF FLUIDS...STAY
IN AN AIR-CONDITIONED ROOM...STAY OUT OF THE SUN...AND CHECK UP
ON RELATIVES AND NEIGHBORS.
TAKE EXTRA PRECAUTIONS IF YOU WORK OR SPEND TIME OUTSIDE. WHEN
POSSIBLE...RESCHEDULE STRENUOUS ACTIVITIES TO EARLY MORNING OR
EVENING. KNOW THE SIGNS OF HEAT EXHAUSTION AND HEAT STROKE. WEAR
LIGHT WEIGHT AND LOOSE FITTING CLOTHING WHEN POSSIBLE AND DRINK
PLENTY OF WATER.
TO REDUCE RISK DURING OUTDOOR WORK...THE OCCUPATIONAL SAFETY AND
HEALTH ADMINISTRATION RECOMMENDS SCHEDULING FREQUENT REST BREAKS
IN SHADED OR AIR CONDITIONED ENVIRONMENTS. ANYONE OVERCOME BY
HEAT SHOULD BE MOVED TO A COOL AND SHADED LOCATION. HEAT STROKE
IS AN EMERGENCY...CALL 9 1 1.

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